In 1851, artist Walter Hartright arrives in Limmeridge, England to teach drawing to wealthy Laura Fairlie. As he walks to the Fairlie estate, he encounters a strange young woman dressed in white, who disappears when a carriage drives up. The passenger, Count Alesandro Fosco, asks Walter if he has passed a woman, explaining that she has escaped from a private asylum, but Walter says nothing. At the house, Walter is greeted by Laura's cousin, Marian Halcombe. The other members of the household are Mrs. Vesey, Laura's old nurse, and Frederick Fairlie, their invalid uncle and heir to the house. The conversation between Walter and Marian is interrupted by Fosco's arrival. Walter then pays a visit to Fairlie, a man with a nervous disposition, who never leaves his rooms, and is struck by the strange atmosphere in the house. The next morning, Walter is introduced to Laura and mistakes her for the woman he met on the road. He soon realizes his mistake, and at breakfast, an amused Laura reveals the story to the rest of the house. Later, Mrs. Vesey admits that many years earlier, there was a little girl at the house, who was about the same age and appearance as Laura. This information prompts Marian to read through old family letters, which confirm Vesey's story and reveal that the girl's name was Ann Catherick. Although Walter asks Marian not to mention the letter to Fosco, the count sees it and surreptitiously removes it. Walter and Laura fall in love, but their romance is ended with the arrival of Sir Percival Glyde, Laura's fiancé. Warned by Marian, Walter decides to leave the house, but before he does, he again encounters Ann, who tells him that she has been kept in an asylum to prevent her from warning Laura. After hearing part of her story, Walter accuses Percival and Fosco of forcing Fairlie to agree to Percival's marriage to Laura. Fosco dismisses Ann as a mentally disturbed woman. Later, when Marian returns to the house after Laura's marriage, she is surprised to learn that the old family servants have been replaced and is shocked by the change in Laura's behavior. Later, Laura tells Marian secretly that she is frightened of her husband, who wants her fortune. Fosco has been drugging Laura in order to gain control of her mind. That night, Ann visits a delusional Laura to warn her against Fosco, but he and Percival frighten Ann to death before she can reveal her secret. They then decide to pretend that Laura is dead and bury Ann in her place. Walter, who has recently returned from Italy, attends the funeral and realizes that the dead woman is Ann. In the meantime, Fosco tries to convince Laura that she is Ann. He is not completely successful, however, and then Laura tells Percival that she is pregnant. Walter and Marian, who have realized that they are in love, travel to the asylum, where Fosco has imprisioned Laura, to try and rescue her from her captors. Laura manages to escape and Walter brings her to the hotel where Marian is supposed to be waiting. However, Marian has returned to Limmeridge to beg Fosco to free her cousin. Fosco then tells Marian that Ann was the illegitimate daughter of Fairlie's sister, and that he married Ann's mother and blackmailed Fairlie in order to get the family fortune. Marian promises to join Fosco if he will write down the entire story. As they speak, Fosco's insane wife enters the room and stabs Fosco, in revenge for the death of her daughter. As he dies, the police, Laura and Walter arrive. Later, Walter marries Marian, and the couple lives together with their daughter and Laura and her son.